The present invention is directed towards providing an active arm support for a typist, the active arm support having adjustability vertically, horizontally and pivotally and in addition providing an adjustable lifting force to minimize typing-related muscle stresses.
The prior art discloses many types of adjustable armrests for use with various types of seats. The Johnson U.S. Pat. No. 4,674,790 discloses an adjustable armrest for an automobile seat wherein the armrest is pivotal and may be set at any preselected height position. The Miller U.S. Pat. No. 4,069,995 discloses a dynamic column support for an arm used in occupational therapy. The arm support is provided with cable members which are laterally deflectable but which will not compress longitudinally. The purpose of the device is to permit free movement in any horizontal direction relative to a fixed base while maintaining a desired balanced condition in the arm. The Aaras U.S. Pat. No. 4,277,102 discloses a chair having armrests which are vertically and angularly adjustable so as to permit the chair to comfortably receive large and individuals. The Wood U.S. Pat. Nos. 4,913,93 and 4,815,688 also disclose armrests which are adjustably mounted for movement vertically and laterally. The Brink U.S. Pat. No. 4,576,351 discloses an armrest for a stroke victim which provides means for receiving an arm in an adjustable angular position. The Perky U.S. Pat. No. 1,970,816 discloses an armrest supported by a spring which permits the arm to adjust to different arm elevations. The Brodersen U.S. Pat. No. 4,828,323 discloses a self-adjusting armrest which is adjustable both in height and slope by means of a ratchet and pawl support mechanism.
The prior art references do not disclose an active arm support structure which functions in the manner disclosed in the present invention. The adjustable active arm support disclosed herein is specifically designed to eliminate nonessential muscle activity of typists and keyboard operators who work for long periods of time in front of video display terminals and the like. More specifically, it has emerged that physical ailments associated with typing are a major category of work related injuries.
The physical problems of repetitive hand and finger motions can be divided into two separate, though interdependent groups. The first group represents problems which develop to the neck, shoulders, and upper arms as a result of the long term holding of the forearms and hands in an appropriate task-related orientation. This category includes such problems as stiff necks and pain between the shoulder blades. The second category of injuries are called overuse syndromes and these cause impairment to the fingers, wrists, hands and forearms. These conditions are often called `repetitive motion disorders`. More specific diagnoses include: carpal tunnel syndrome, focal dystonia, trigger finger, tendonitis, etc.
The present invention seeks to overcome these problems by providing task-active forearm and arm support from the elbow to the wrist.
An object of the present invention is to provide compatibility of the active arm support with a particular typist and a particular work station environment. This is accomplished with two specific adjustments. First, the active arm support is laterally adjustable so as to accommodate different body widths. Second, the active arm support is vertically adjustable so as to accommodate different body lengths and workstation heights.
Thus adjusted, another object of the present invention is to provide a work-performing function through active arm support. This is accomplished by the following elements. First, the active arm support pivots horizontally. This pivoting movement is activated simply by the lateral movement of the forearm during typing. More importantly however, a spring hinge is provided which produces a variable, vertical lift on the active arm support while it fully supports the entire forearm. The net result of these support vectors is a spring-assisted universal joint at the elbow.
Specific muscles which are weight supported during keyboard operation include the Deltoids, the Biceps, the Triceps, the finger flexors and extensors, and others.
Other objects and many of the attendant advantages of the present invention will become more readily apparent on consideration of the following detailed specification in connection with the accompany drawings.